过氧化氢对小鼠心肌细胞钙离子通道的影响

Effects of hydrogen peroxide on L-type calcium channel in ventricular myocytes of mice

目的观察过氧化氢(H2O2)对小鼠心肌细胞L型钙离子通道的作用机制。方法应用膜片钳技术中的单通道记录观察1 mmol/L H2O2对心肌细胞钙离子电流的影响,并观察钙调素依赖性蛋白激酶Ⅱ(Ca MKⅡ)抑制剂(KN93)及半胱氨酸的氧化剂5,5’-二硫双(2-硝基苯甲酸)(DTNB)对细胞钙离子电流及通道活性的影响。结果 1 mmol/L H2O2可使钙离子通道中钙离子电流显著增加,钙离子通道活性增加至(206±32)%,Ca MKⅡ的抑制剂KN93并未完全抑制H2O2引起的钙离子通道活性增加;取单片细胞膜组织进行观测,排除细胞内原有物质,特别是Ca MKII的干扰,H2O2依然能引起钙离子通道活性的增加;半胱氨酸的氧化剂DTNB在细胞膜内面向外模式中可提高离子通道活性(P<0.01),而随后加入的1 mmol/L H2O2不再明显增加钙离子通道活性(P>0.05)。结论 H2O2对小鼠心室肌细胞钙离子通道的作用可能是通过对通道上的半胱氨酸直接氧化而产生的。

Objective To observe the effects of hydrogen peroxide（H2O2） on L-type calcium（Ca2＋） channel in isolated ventricular myocytes of mice. Methods Effects of 1 mmol/L H2O2 on L-type Ca2 ＋channel in isolated ventricular myocytes of C57BL/6mice were observed by single channel recording of patch clamp technique,as well as KN93 [inhibitor of calmodulin-dependent protein kinase Ⅱ（Ca MKⅡ）] and DTNB（oxidant of cysteine）. Results H2O2 increased the activity of L-type Ca2＋channel[（206 ±32）% ] compared with the control（ P 〈0.01）. KN-93 partially attenuated the H2O2-induced increase of the activity of L-type Ca2 ＋channel. DTNB increased the activity of L-type Ca2 ＋channel with inside-out configuration, which couldn ＇t be activated by 1 mmol/L H2O2 added after DTNB（P 〉0.05）. Conclusion H2O2 may facilitate the L-type Ca2 ＋channel through oxidation of cysteine.